Using biopsy-derived human skin cells in culture, age dependence of cell migration and the motile activity of surface projections will be studied in cells from young (21-36 yrs.) and old (63-92 yrs.) donors by new and quantitative techniques developed by the applicant. In addition, scanning electron microscopy will be used to examine a possible age dependence of the surface morphology of the cells. Their cytoplasmic and surface architecture will be probed by transmission electron microscopy and by localizing by indirect immunofluorescence actin, myosin, tubulin, and LETS protein in the cells. The resulting quantitative and qualitative data will be compared as to donor age, passage number after biopsy and the quiescent or pre-quiescent state of the cells. The proposed study of such cells from truly aged tissue is to reveal whether motility or motility-related parameters express cell age and whether cell lines can be found which express similar changes as their passage number in culture increases.